Define the term relative atomic mass.

A sample of magnesium containing the isotopes ${}^{24}Mg$, ${}^{25}Mg$ and ${}^{26}Mg$ has a relative atomic mass of $24.32$. The sample contains $78.0\%$ of the ${}^{24}Mg$ isotope. Calculate the percentage abundance of each of the other two isotopes.

State, in terms of the numbers of fundamental subatomic particles, one similarity and one difference between atoms of ${}^{24}Mg$ and ${}^{26}Mg$.

Give two reasons why it is necessary to ionise the isotopes of magnesium before they can be analysed in a TOF mass spectrometer.

A ${}^{25}{Mg}^{+}$ ion travels along a flight tube of length $1.20m$. The ion has a constant kinetic energy ($KE$) of $6.465\times 10^{-14}J$.

Where:

• $m=$ mass of the ion in $kg$
• $v=$ speed of the ion in $m{s}^{-1}$

Calculate the time, in $s$, for the ${}^{25}{Mg}^{+}$ ion to travel down the flight tube to reach the detector. The Avogadro constant, $L=6.022\times 10^{23}{mol}^{-1}$.